In recent years, there has been a tendency that ordinary houses have no toilet for men or urinal because the toilet is presumed to be shared by men and women.
On the other hand, office buildings and other commercial facilities have toilets for men and those for women separately. Therefore, commercial facilities still have demand for urinals.
In connection with the recent growing consciousness of environmental issues, demand for water saving and/or CO2 emission reduction is becoming stronger.
However, if the quantity of cleaning water is reduced for the purpose of water saving, it is difficult to flush away the urine adhering to the urinal. The urine which has not been flushed away might cause a bad smell and smell up the toilet for men.
In other words, urinal cleaning and water saving are contradictory and water saving in urinals has been very difficult.
Besides, it is well known that in the use of a urinal, urine which has collided against the urinal splashes over a wide area as droplets. The urine droplets which have splashed over a wide area are not all flushed away with cleaning water but some remain around the urinal.
Also, since urine is organic, the remaining urine droplets may putrefy and give off a bad smell.
Furthermore, another problem is that if filth exists in the urinal drain (urine drain) pipe line, urine may stay and accumulate around the filth and consequently become a urine stone which may clog the drain pipe line.
For example, another conventional technique is that ozone gas and tap water are supplied to an injector and homogenously mixed and stirred to generate ozone water and the generated ozone water is supplied to the urinal (see Patent Document 1).
However, in such conventional technique, anything about when to supply ozone in urination and how to control ozone supply is not disclosed, making it difficult to do automatic cleaning of the urinal effectively. In addition, the above problem cannot be solved.    Patent Document 1: Japanese Patent Application Laid-Open Publication No. 2001-241086